Iraq's finance minister has accused a "militia force" of kidnapping members of his staff, saying he holds the prime minister personally responsible for their safety.

Finance Minister Rafia al-Issawi made the accusations in a late night press conference Thursday. The move is certain to enflame Iraq's ongoing political tensions.

Al-Issawi is a member of the Sunni-backed Iraqiya bloc, Prime Minister Nouri al-Maliki's main political rival. He was flanked by senior members of his political bloc during the televised address. Al-Maliki's spokesman could not immediately be reached for comment.

The accusations come hours after Iraq's ailing president was flown to Germany for medical treatment following a stroke.